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Critical thresholds for stage division of water erosion process in different ridge systems in mollisol region of Northeast China

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Journal of Mountain Science 2023年第6期20卷 1540-1560页

作者： JIAO Jian QIN Wei LI Kun-heng XU Hai-chao YIN Zhe HOU Shu-yan State Key Laboratory of Simulation and Regulation of water Cycle in River Basin China Institute of Water Resources and Hydropower ResearchBeijing 100038China Research Center on Soil and water Conservation of the Ministry of water resources Beijing 100048China School of Soil and water Conservation Beijing Forestry UniversityBeijing 100083China Heilongjiang Province Hydropower Research Institute Harbin 150070China

Extreme rainfall events on a slope under ridge tillage systems cause concentrated stream soil *** analyse the critical thresholds for different stages of water erosion process of ridge systems,simulated rainfall-erosion experiments for the contour wide ridge(CWR),contour narrow ridge(CNR),longitudinal wide ridge(LWR),and longitudinal narrow ridge(LNR)were conducted under four rainfall intensities,with slope gradients of 3°and 5°.For the runoff event,the runoff depth order was LNR>LWR>CWR>CNR;the soil loss order was CNR>LNR>CWR>*** product of slope factor(S)and rainfall erosivity(R)or runoff depth(D),can be adopted as critical thresholds for different stages of runoff and soil erosion *** the longitudinal ridge systems,R values were provided for LWR and LNR and were the beginning of sheet flow,whereas the product of rainfall erosivity and slope factor(RS)values were provided for LWR and LNR as the beginning of the accelerated concentrated *** the contour ridge systems,R values were provided for CWR and CNR as critical thresholds for the beginning of *** product of runoff depth and slope factor(DS)values were 9.98 and 7.73 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of ridge failure;the DS values were 18.45 and 12.75 mm for CWR and CNR,respectively,and were critical thresholds for the beginning of the formation of ephemeral gully *** critical thresholds can distinguish different stages of soil erosion process modelling.

关键词： Runoff Soil loss Threshold Ridge failure Artificial rainfall simulation

Climate change and groundwater resources in Lao PDR

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Journal of Groundwater Science and Engineering 2017年第1期5卷 53-58页

作者： Khongsab Somphone OunakoneKone Xayviliya division of Groundwater Department of Water Resources MoNRE

The national economy of Lao PDR is highly dependent on water resources. Consequently, the sustainable management of groundwater and successful adaptations to future climate change are major concerns. Climate projections for Lao PDR predict increased rainfall and hot weather, with more intense rainfall events and more frequent and severe droughts and floods. Under climate change, reductions in the amount and quality of groundwater are two critical problems. Reductions of the groundwater level will restrict the access of local people to groundwater resources, thereby posing a threat to food security and livelihoods. Lao PDR suffers from a limited number of human resources with the requisite skills to perform groundwater investigations and provide sustainable management. For the successful implementation of groundwater management plans, limitations associated with funding and technology should be resolved via support from the government and international cooperation. Advanced action plans for capacity building and training courses should be established to strengthen administrative and individual capacities. Technical measures, such as groundwater monitoring, aquifer characterizations, and water treatment systems, should be implemented to manage future climate change and water resource security.

关键词： Groundwater water resource Climate change LaoPDR

Direct numerical simulation of matrix diffusion across fracture/matrix interface

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water Science and Engineering 2013年第4期6卷 365-379页

作者： Yong ZHANG Eric M.LABOLLE Donald M.REEVES Charles RUSSELL division of Hydrologic Sciences Desert Research Institute Department of Land Airand Water ResourcesUniversity of California

Accurate descriptions of matrix diffusion across the fracture/matrix interface are critical to assessing contaminant migration in fractured media. The classical transfer probability method is only applicable for relatively large diffusion coefficients and small fracture spacings, due to an intrinsic assumption of an equilibrium concentration profile in the matrix blocks. Motivated and required by practical applications, we propose a direct numerical simulation （DNS） approach without any empirical assumptions. A three-step Lagrangian algorithm was developed and validated to directly track the particle dynamics across the fracture/matrix interface, where particle＇s diffusive displacement across the discontinuity is controlled by an analytical, one-side reflection probability. Numerical experiments show that the DNS approach is especially efficient for small diffusion coefficients and large fracture spacings, alleviating limitations of the classical modeling approach.

关键词： Key words: fracture matrix interface direct numerical simulation transfer probability Lagrangian algorithm

Capacitive sensing technique for silt suspended sediment concentration monitoring

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International Journal of Sediment Research 2010年第2期25卷 175-184页

作者： Yin-Sung HSU Shih-Yi YUAN Chia-Ling CHANG Kao-Chung CHANG Feng Chia University division Chief of water resources Agency Ministry of Economic Affairs

Automated, real-time, and continuous techniques for monitoring suspended sediment concentration in rivers and reservoirs can play an important role in the improvement of the quantity and quality of sediment data, and are valuable to the management of water environment, water conservancy, hazard prevention, and water resources. Research in the monitoring techniques has examined the possibility of using the characteristics of dielectric constants for detecting soil moisture and concentration of air-water two-phase flow, based on the fact that dielectric constants of sediment, air and water are different. A capacitance sensor was developed to monitor the silt suspended sediment concentration (SSSC) in a recent study, following the principle that as SSSC increases in the sediment-water mixture, the apparent dielectric constant of the water sample also increases and therefore the capacitance detected by the sensing system also increases. It is demonstrated that the variations in the concentration of silt sediment correlates positively with the variations in observed capacitance in a linear fashion, and correlates negatively with voltage outputs but also in a linear fashion. The correlation coefficients reached above 0.98. The overall errors in estimated concentrations range between 0.26% and 2.91%. Elements in the capacitance sensor system such as the frequencies of the signal generating system, areas of the electrode plates, and effects of sample temperature have also been evaluated. The results illustrated that the capacitance sensor techniques can be applied to monitoring SSSC automatically and continuously. Also, the range of SSSC in the experiment reached 200 kg/m3; therefore, the application of this technique in practical SSSC monitoring is worthy of further research.

关键词： Silt suspended sediment concentration Sediment sampling Automated continuous measurement Capacitive sensing system Dielectric material Silt sediment

Textural and depositional processes of surface sediments of Kalpakkam, Southeast Coast of India

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Frontiers of Earth Science 2012年第4期6卷 392-404页

作者： Usha NATESAN K. Deepthi AL. MUTHULAKSHMI Vincent A. FERRER S.V. NARASIMHAN V.P. VENUGOPALAN Centre for water resources Anna University Chennai 600025 India water and Steam Chemistry division Bhabha Atomic Research Centre Kalpakkam 603102 India

To understand the influence of human dis- turbance on the sediment processes along Kalpakkam coast, India, beach and seabed sediments at 200 m, 500 m, and 1 km into the sea were collected monthly for one year and analyzed. Coarser material close to the tidal inlets （river） and manmade structures （sea wall） indicate the effect of these features in altering the grain size distribution from the general trend. The bivariant plots confirm the dominance of deposition under beach environment. The CM diagram （C-one percentile grain diameter, M - median） divulges that the deposition takes place by suspension and rolling of sediments with C 〈 1 mm. Linear discriminate function analysis for sediments at Kalpakkam indicates a shallow marine environment for all the samples collected. On the multigroup multivariant discriminant functions V1 -V2 diagram, the bulk of the samples from Kalpakkam to Mahabalipuram fall in the field of beach deposition. These results show that reworked sediments, submerged during the Holocene marine transgression are being deposited on present-day beaches by waves, currents and rivers in the study area. Though a high wave energy environment is prevailing in the study area, dominant northward sediment transport along the Kalpakkam-Mahabalipuram human interventions. Beach coast is not altered due to building activity in front of the sea wall ensures the safety of Indira Gandhi Centre for Atomic Research （IGCAR） from wave actions without causing any significant changes to the coastal environment.

关键词： beach depositional environment grain size Kalpakkam seabed sediment

Experimental study on desorption of soluble matter as influenced by cations in static water

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water Science and Engineering 2014年第4期7卷 384-394页

作者： Wen-sheng XU Li CHEN Xiao-xia TONG Xiao-ping CHEN Ping-cang ZHANG division of Soil and water Conservation Changjiang River Scientific Research Institute State Key Laboratory of water resources and Hydropower Engineering Science Wuhan University

With variation of drainage basin environments, desorption of soluble matter has become one of the significant erosion processes in rivers. It has a considerable impact on flow and sediment transport, as well as processes of river bed deformation and landform evolution throughout a watershed. In this study, considering influences on sediment movement, especially on cohesive sediment transport, Ca^2＋ and H^＋ were chosen as characteristic ions of soluble matter, and the total desorption quantity of Ca^2＋ and pH value when the desorption equilibrium is reached were employed as two indexes representing the desorption of soluble matter. By means of an indoor experiment, desorption of soluble matter as influenced by cations in static water was investigated. The results show that the total desorption quantity of soluble matter increases with the initial cation concentration until a maximum desorption quantity value is obtained and maintained. The total desorption quantity of soluble matter depends on properties of the specific cations in static water, and the stronger the affinity is between the cation and sediment surface, the higher the total desorption quantity will be. Finally, a strong approximate linear relationship between desorption quantities for different kinds of soluble matters was obtained, which means that variation of pH values can accurately reflect the desorption results of soluble matter.

关键词： soluble matter desorption cation sediment static water indoor experiment

Decoding complexity: the need to enhance precision and streamline spatial understanding in neuroscience

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Neural Regeneration Research 2025年第3期20卷 801-802页

作者： Sameehan Mahajani Armita Salahi Brenda Gonzalez Charlotte Nelson Frank Hsiung Biology&Applications division NodexusSan JoseCAUSA

Neuroscience is the ultimate frontier in our quest for a comprehensive understanding of human behavior. Since its launch in 2009, the Human Connectome Project has emerged as a pioneering force, making heroic strides i... 详细信息

关键词： behavior frontier dating

Hydraulics of crest spillway with large unit discharge and low Froude number

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Journal of Hydrodynamics 2015年第2期27卷 242-247页

作者：吴建华李程纯子马飞李同春吴伟伟 National Engineering Research Center of water resources Efficient Utilization and Engineering Safety College of Water Conservancy and Hydropower EngineeringHohai University Hydraulic Structures design division Hydrochina Huadong Engineering Corporation

With respect to the crest spillway with large unit discharge and low Froude number, the hydraulics of the slit-type energy dissipater at the outlet should be noticed due to the complicated flow regimes. In the present paper, some issues about hydraulic characteristics were experimentally investigated by means of five slit-type outlets and four tetrahedrons, including the flow choking, impact to river banks and jet trajectory. The main findings are as follows. The critical Froude number for the flow choking decreases with increasing outlet width of the slit-type energy dissipater. If the flow Froude number is expressed by the parameters just before this energy dissipater, the tetrahedron placed inside the side wall of the outlet could efficiently avoid the flow impact to the river bank of same side, and compared with the jet trajectory of the slit-type energy dissipater, the outlet with tetrahedron has different trajectory trend, i.e., the distance of the jet trajectory decreases with the increase of the water head due to special form of the outlet tetrahedron.

关键词： large unit discharge low Froude number flow choking impact to river bank jet trajectory

Vagus nerve stimulation in intracerebral hemorrhage:the need for further research

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Neural Regeneration Research 2025年第11期20卷 3213-3214页

作者： Sheharyar S.Baig Ali N.Ali Arshad Majid Sheffield Institute for Translational Neuroscience Division of NeuroscienceThe University of SheffieldSheffieldUK

Vagus nerve stimulation(VNS)and stroke:Stroke is the second leading cause of death and the third leading cause of disability worldwide(Baig et al.,2023).There have been significant paradigm shifts in the management of acute ischemic stroke through mechanical *** chronic ischemic stroke,invasive VNS paired with rehabilitation is associated with a significant increase in upper limb motor recovery and is FDA-approved(Baig et al.,2023).There are no treatments of similar efficacy in acute intracerebral hemorrhage(ICH)where several promising trials,e.g.,TICH-2,STOP-AUST,and TRAIGE did not show improvements in functional outcomes(Puy et al.,2023).

关键词： stimulation acute